Flow spreading device

ABSTRACT

A DEVICE FOR TRANSFERRING STOCK COMPRISING INLET MEANS ADAPTED TO RECEIVE STOCK FROM A SOURCE, TANK MEANS ADAPTED TO RECEIVE STOCK FROM SAID INLET MEANS, SAID INLET MEANS BEING ATTACHED TO SAID TANK AND POSITIONED PARTIALLY INTERIORLY OF SAID TANK, WALL MEANS FORMING A PART OF SAID TANK MEANS AND POSITIONED PERPENDICULAR TO THE DIRECTION OF FLOW OF STOCK FROM SAID INLET MEANS TO FORM STOCK DIRECTION CHANGING MEANS, OUTLET MEANS ADAPTED TO REMOVE STOCK FROM SAID TANK, OUTLET MEANS BEING ATTACHED TO SAID TANK AND POSITIONED PARTIALLY INTERIORLY OF SAID TANK AND PRESSURE MEANS ATTACHED TO SAID TANK AND ADAPTED TO CREATE A PRESSURE IN SAID TANK GREATER THAN THE PRESSURE DOWNSTREAM FROM SAID OUTLET MEANS. SAID OUTLET MEANS COMPRISING A PLURALITY OF UNIFORMLY SPACED UNIFORMLY SIZED TUBES EXTENDING FROM WITHIN SAID TANK TO A POINT EXTERIOR OF SAID TANK. IN ADDITION THE INLET MEANS IS PREFERABLY A PLURALITY OF TUBES EXTENDING INTO THE TANK. IN YET ANOTHER EMBODIMENT, THE INLET MEANS FURTHER INCLUDES A HEADER IN COMMUNICATION WITH THE INLET TUBES AT A POINT EXTERIOR OF SAID TANK AND ADAPTED TO PASS STOCK IN A DIRECTION PERPENDICULAR TO THE TUBES AND DRAIN THE TANK. PREFERABLY, THE HEADER IS TAPERED SUCH THAT THE CROSS-SECTIONAL AREA OF THE HEADER DECREASES IN THE DIRECTION OF STOCK FLOW IN SAID HEADER MEANS.   D R A W I N G

Aug. 10,1971 D. A. GODDARD 3,598,698

FLOW SPREADING DEVICE Filed Oct. 14. 1968 INVENTOR.

DEN/5 A. GODDARD.

United States Patent 3,598,698 FLOW SPREADING DEVICE Denis A. Goddard, Beloit, Wis., assignor to Beloit Corporation, Beloit, Wis. Filed Oct. 14, 1968, Ser. No. 767,449 Int. Cl. D21f 1/02 US. Cl. 162-340 5 Claims ABSTRACT OF THE DISCLOSURE A device for transferring stock comprising inlet means adapted to receive stock from a source, tank means adapted to receive stock from said inlet means, said inlet means being attached to said tank and positioned partially interiorly of said tank, wall means forming a part of said tank means and positioned perpendicular to the direction of flow of stock from said inlet means to form stock direction changing means, outlet means adapted to remove stock from said tank, outlet means being attached to said tank and positioned partially interiorly of said tank and pressure means attached to said tank and adapted to create a pressure in said tank greater than the pressure downstream from said outlet to form means for moving stock through said outlet means. Said outlet means comprising a plurality of uniformly spaced uniformly sized tubes extending from within said tank to a point exterior of said tank. In addition the inlet means is preferably a plurality of tubes extending into the tank. In yet another embodiment, the inlet means further includes a header in communication with the inlet tubes at a point exterior of said tank and adapted to pass stock in a direction perpendicular to the tubes and drain the tank. Preferably, the header is tapered such that the cross-sectional area of the header decreases in the direction of stock flow in said header means.

The transfer of stock from one chamber to a second chamber oftentimes becomes quite critical as the particular use to which the particular stock is subjected to becomes more complicated. For example, it is necessary to transfer fluid suspensions of solids such as, for example, colloidal silica sols for use in a particular process. It is necessary to maintain these solutions or suspensions in a dynamic state to maintain their stability. However, the ultimate use to which these materials are put oftentimes requires little or no pulsing, Which occurs from pumps and mixing devices used to create the constant dynamic motion necessary to stabilize the material. Of particular importance, and hereinafter more fully described as reference to the preferred embodiment, is the transfer and handling of paper pulp stock. By its very nature, suspensions of cellulosic fibers in water require certain outside forces to maintain a uniform and uncoagulated suspension. Dilute solutions in the range of one to five percent cellulosic fibers in water undergo flocculation, coagulation and other phenomena which disrupt the uniformity of the suspension.

The many ways which have been employed in the prior art to maintain these suspensions of solids in liquids, which is referred to as stock in the present disclosure, have caused the formation of pulses or surges in the lines transferring and holding these stocks. For example, as in the preferred embodiment of paper pulp suspension transfer, the pumps necessary to transfer the dilute suspensions of wood fibers in water cause an unevennes in flow. Applications of these uneven flows to Fourdrinier wires and other paper making devices causes a nonuniform dispersion of the stock on the forming medium, thereby resulting in a nonuniform product.

Accordingly, it is an object of this invention to provide 3,598,698 Patented Aug. 10, 1971 ice a means for transferring stock such as suspensions of cellulosic fibers in water from one point to another while maintaining the dynamic equilibrium necessary for a complete suspension without the attendant disadvantages of pulsation and surges.

It is another object of this invention to provide a uniform flow of paper pulp stock to a device for forming paper which can be readily fitted into the normal papermaking process whereby stock is continuously transferred from stock chests to the paper forming device or headbox.

Other objects will become apparent from a further reading of the present disclosure.

It has now been discovered that uniform transfer of suspensions of solids in fluids can be achieved without pulsing, surging, or other nonuniformities of flow according to the present invention. Basically the invention comprises the use of an inlet means adapted to receive stock from a source, a tank means adapted to receive stock from the inlet means, whereby the inlet means is attached to the tank and positioned partially interior to the tank, and where the tank includes wall means forming a part of the tank and positioned perpendicular to the direction of flow of the stock through the inlet means. Further provided are outlet means adapted to remove stock from the tank, where the outlet means are also attached to the tank and positioned partially interior of the tank. Finally, pressure means are provided to create a pressure within the tank greater than the pressure downstream from the outlet to form means for moving the stock through the outlet means.

For a more complete understanding of the invention, with particular emphasis placed upon the preferred embodiment described herein, reference is hereby made to the drawing, in which:

The figure represents a schematic section view of the preferred embodiment of the present invention.

As shown in the drawing, an inlet means 11 is adapted to transfer stock from a source hereinafter described. In the present embodiment, the inlet means 11 consists of a plurality of tubes extending into the tank. The tank itself is defined by sidewalls 12, bottom wall 13 (upon which the inlet tubes 10 are attached) and top wall 14. Positioned within the tank and attached to the sidewall 12 is a wall means 16 which forms a part of the tank means and is positioned perpendicular to the direction of flow 11 from the inlet means 10. This wall means 16 positioned perpendicular to the flow 11 of the stock through the inlet 10 forms a stock direction changing means.

Also provided as shown in the drawing are outlet means 18 which are adapted to remove stock from the tank. The outlet means 18 are attached to the tank at wall 14 and are positioned partially interiorly of the tank. In a preferred embodiment, the outlet means 18 comprises a plurality of uniformly spaced, uniformly sized tubes extending from within the tank to a point 22 exterior of the tank. The purpose of the uniformity of spacing and size is to provide a uniform distribution of the material or stock as it leaves the tank through the outlet means 18. Thus it is possible to uniformly distribute the stock over the entire width of the walls 12, and allows the transfer of, as in the present embodiment, paper stock to a headbox 24 for use in the formation of paper.

Also provided as a part of the present invention is a pressure means comprising a pump 20 and a pressure inlet 21 which is attached to the sidewall 12 of the tank and is adapted to create a pressure within the tank above the stock level 17 which is greater than the pressure downstream of the outlet 18 at a point 22 exterior of the tank, thereby forming means for moving stock to the outlet means 18. By the use of a suitable difference in pressure inside of the tank over the outside of the tank, various flow rates through the outlet tubes 18 will be elfected. By the use of a plurality of uniformly spaced, uniformly sized outlet tubes 18 which have a total cross-sectional area less than the cross-sectional area of the inlet tubes 10, the effect of introduction of stock into the tank through inlet will cause a quantity of stock to exit through the outlet tubes 18. However, since the cross-sectional area of the outlet tubes is less, the stock will be forced to pass through the outlet tubes 18 at a higher velocity, thereby insuring a uniform and complete dispersion of the solid material in the fluid carrying media. Thus, in the example of paper stock, any fiocs or coagulated fiber bundles would be broken up and/ or dispersed in the high velocity flow through the outlet tubes 18.

In a preferred embodiment of the present invention, further reduction in the effect of pulses and/or surges is effected by the use of a header attached to the inlet means and positioned exterior of the tank. Shown in the figure, is a header 26 which is tapered from a cross-sectional area at point shown by 26 down to a header size of smaller cross-sectional area at the other end 26a. Of course, it is necessary to flow stock in the direction of the decrease of cross-sectional area.

Thus, in the operation of the present invention, as illustrated by a preferred embodiment shown in the figure, stock would flow through the header in the direction of decreasing cross-sectional area. A quantity of stock would also pass upwards through the plurality of inlet tubes 10 in the direction shown by arrow 11. As the stock exited from the inlet tubes 10 in the direction of arrow 11, the stock would impinge upon the perpendicular wall means 16, thereby causing a change in the direction of flow of the stock. The stock would collect in the tank and would rise to a level shown by level 17. The pump 20 would cause a flow of air pressure or other pressure forming means through line 21 to cause or create a pressure inside the tank which is greater than the pressure at a point exterior the tank 22 downstream from the outlet. At a point where equilibrium was reached, the stock would then pass through the outlet tubes 18, which tubes would cause a uniform spreading of the stock across the entire width of the walls 12 and therefore permit the uniform distribution of stock to the headbox 24. All pulses and other irregularities in flow caused by the treatment of the stock prior to the inlet tubes 10 would be dissipated by impingement of the stock on the perpendicular wall 16 and result in holding time at which any one portion of the stock would be kept within the tank. Exiting of the stock through the outlet tubes 18 would redisperse any portion of the stock which had become nonuniform in suspension, and, since the outlet tubes 18 would be drawing from a constant pressure force, there would be no pulsation or surges in the flow through the tubes 18.

While the present invention has been shown in a preferred embodiment to relate directly to the production of paper, by showing the transfer of paper pulp stock to a point just prior to the formation means in a paper making process, it will become readily apparent to those skilled in the art that a wide variety of applications will be found which can readily employ the present invention.

Having thus described the invention, what is claimed is:

1. A headbox assembly for a papermaking machine comprising in combination:

an inlet header for stock flow having inlet tubes, a pulse modulating tank having said inlet tubes connected to discharge into the tank,

means forming a stock level in the tank, means delivering air to the top of said tank to form an air head above the stock level in the tank,

a stationary stock impingement wall in said tank positioned to receive and disperse stock discharged from the tubes,

a stock receiving headbox for delivering the stock to a slice for distributing the stock to a traveling forming surface,

and outlet tubes connecting between said receiving headbox and said tank and having stock entry ends spaced inwardly from the walls of the tank and removed from said impingement wall and below said stock level and also below the outlet of said inlet tubes in the tank so that stock enters the entry ends from all directions and irregularities and pulses in flow in the tank are dissipated in the tank in various directions from said entry ends.

2. The structure of claim 1 wherein said outlet tubes are uniformly spaced and uniformly sized.

3. The structure of claim 1 wherein said inlet tubes are uniformly spaced and uniformly sized.

4. The structure of claim 1 wherein said inlet header is tapered such that the cross-sectional area of said header decreases in the direction of stock flow through said header.

5. The structure of claim 1 wherein the cross-sectional area of said outlet tubes is less than the cross-sectional area of said inlet tubes.

References Cited UNITED STATES PATENTS 3,328,237 6/1967 Notbohm 162-343 3,486,972 12/1969 Nagell 162-336X REUBEN FRIEDMAN, Primary Examiner T. A. GRANGER, Assistant Examiner 

